Container for storing oil and like fluids



Dec. l, 1953 H. EDHOLM 2,661,062

CONTAINER vFOR STORING OIL AND LIKE FLUIDS Filed June 26, 1950 4 Sheets-Sheet l mvENToR. HA RALD E DHOLM BY Lf( ATTORNEYS.

Dec. l, 1953 H. EDHoLM 2,661,062

CONTAINER FOR STORING OIL AND LIKE FLUIDS Filed June 26, 1950 4 Sheets-Sheet 2 INVENTOR. HA RA/ D EDHOLM BYAw-wr ATTORNEYS.

Dec. 1, 1953 H. EDHoLM l CONTAINER FOR STORING OIL AND LIKE FLUIDS Filed June 2e, 195o 4 Sheets-Sheet 5 mvENTR. HA ,QA/ 0 EDHOLM ATTORNE s.

Dec. l,r 1953 fH. EDHOLM 2,661,062

CONTAINER FOR STORING OIL AND LIKE FLUIDS Filed June 26, 1950 4 Sheets-Sheet 4 INVENTOR. K

HARALD EDHOLM ATTORNEYS.

Patented Dec. 1, 1953 CONTAINER FOR STGR/ING OIL AND LIKE FLUIDS Harald Edholm, Solsidan, Saltsjobaden, Sweden Application June 26, 1950, Serial No. 170,333

Claimspriority, application Sweden June 28, 1949 (Cl. 16B-1) 14 Claims.

This invention relates to undergroumiY containers for storing water-immiscible fluids hav.- ing specific gravities less than that of Water, and in particular relates to storage of such liquids inunderground cavities having pervious Walls.

The storage of liquids such as oil, gasoline, or the like in metal containers above ground is well known. Storage in metal or concrete containers below ground is also known but involves particular diiculties not only in maintenance of the containers but inthe provision of the cavities for their reception.

In accordance with the present invention, provision is made for the storage of oil,V gasoline, or the like in underground cavities having pervious walls. Briefly stated, this is Amade possible by taking advantage of vulrlderground water pressure to cause water to seep intothe cavity and by virtue of such seepageA and the attendant hydraulic pressure exerted inwardly to insure against loss of the storedy liquid. In accordance with theinvention, controls are exercised, as will appearfhereafter, to. maintain the required pressure conditions andv to remove` accumulation of water as well as to maintain proper control irrespective of Vvariations in the. volume of the stored liquid.

Leakage of water into a highly mobile oil is generally not harmful provided the `water sinks to the provision and control of a subsurface container of the type indicated. These and other objects of the invention particularly relating to details of construction and control will become apparent from the following descriptionread in conjunction with the accompanying drawings, in which:

Figure 1A shows. a section of .one form of container, there being associated therewithv at its left a pressure diagram explanatory of condi tions which exist in and about the container;

Figure 1B is a similar showing ofan alternative form of container with a diagram showing the conditions existing in and about the container;

Figures 2, 3 and 4 are sections through several Referring iirst to Figure 1A, there is illustrated therein a container provided in accordance with the invention in its simplest elementary form of an open topped unlined cavity a in the earth. The walls of this cavity are per meable through all or some portions thereof.. The ligure shows oil oating on water in the-- cavity, the oil-water interface being indicated at 8. The term oil may be herein considered to be generic to Water immiscible liquids having Aa speciiic gravity less than water (fresh or salt) and may be considered to include such mobile liquids as gasoline, or the like.

below the lowest water level attained therein,

which pipe provides for the introduction or re* The pipes 9 and il] may be moval of water. assumed associated with pumps as will hereafter appear in the more specific disclosure. The level of the subsoil water in the ground and which may be assumed to permeate the cracks and pores in the entire region about the con tainer is indicated at hg. The level of the surface of the oil is designated hoi. water in the pipe 9 is designated hvi.

.At the left of Figure 1A there is provided an..

pol: 1 (hol-h) and this equation is that of the line v1 having an. abscissa value of 0 at h=hfv1. In the fore# going equation 1 is the proportionality factor suitable for the units of pressure and height and corresponds to the specilic gravity of water involved. Similarly, in the case of the column of oil existing in the cavity, the pressure and this equation is that of the line o1 but the proportionality factor corresponds to the units There is indicated. at I9 a pipe through which the oil is introduced or withdrawn, While there is indicatedY at 9 a pipe open at the bottom of the cavity- The level of The el ci) the diagram. It will be evident that if the level of the oil surface is to be maintained constant, Water must be introduced or removed through pipe 9 as the oil is removed or introduced or in correspondence with water seep-age into the container. 1f the quantity of oil in the container remains constant over a period of time, water must be removed through pipe 9 at the same rate as that at which it enters through the container walls. From the practical standpoint, of course, such removal of water may be effected intermittently rather than continuously to maintain approximately constant level of the oil surface. Alternatively, if oil is removed at a rapid rate such that seepage throughout the time of removal is negligible, water must be introduced at a volumetric rate corresponding to the volumetric rate of oil removal. Similar reverse conditions are involved to take care of the introduction of oil, the interface level 8 being co1'- respondingly lowered as oil is introduced. In actual practice, of course, during removal or introduction of water, some water seepage will occur into the container and the rates of water flow will be correspondingly adjusted.

The foregoing indicates the maintenance and attainment of the desired equilibrium conditions in the container. For proper storage conditions these must be correlated with the water conditions existing outside the container so as to insure water flow inwardly through the pervous walls at all levels at which the oil contacts the pervous walls of the containers. This condition is assured if the pressure exerted by the stored oil at any point on the pervous wall of the container is maintained at a pressure less than that exerted by the subsoil water at the same point.

Assuming, for example, that the level of the subsoil water is at hg immediately outside the wall of the container, the pressure curve of the subsoil water outside the container will be as indicated at g in the diagram. The straight line constituting this curve has the same slope as the line constituting curve v1. It will be evident that this curve represents at any level of contact of oil with the container walls excess of external subsoil water pressure over the oil pressure o1. These conditions are proper for storage since water will then continuously seep inwardly into the container through all cracks or ssures and now of oil outwardly will be prevented. The water thus seeping inwardly will flow downwardly along the walls of the container, accumulating in the pool of water below the interface 3. Under most actual conditions, however, there is another factor to be considered, namely, the so-called cone of depression which exists whenever water is withdrawn from a well or its equivalent and the water can flow to the well only through passages offering someresistance to flow. In the vicinity of the well the surface of the water will be below the level of the surface at more remote locations and the local depression of the surface forms the cone of depression which in Figure lA is indicated at 2. If such cone of depression exists, the more remote water level hg will not represent the effecwsame level hg around the entire container.

tive level at the container walls, but the latter level will be somewhat lower in the case of a container such as in Figure 1A. This must be taken into account and the upper most limit for the level of the oil surface will be below the lowest level of this cone of depression. Such a condition is, of course, achieved by proper withdrawal of water from the pipe 9.

The conditions just indicated, however, are not the only ones which must be taken into account in determining the maximum height of the surface of the oil. The level of the subsoil water in most localities, i. e. the water table is subject to seasonal or other periodic fluctuations and in the case of a container of the simple type illustrated in Figure lA such variations may seriously limit the oil level, requiring the earth cavity to be excessively deep with attendant increase in its initial cost of production and with wastage of volume. Accordingly, the upper portion of the cavity may be lined with an impervious liner as will now be described with reference to Figure 1B.

In Figure 1B the cavity b is provided with a liner 3 at its upper portion extending from the surface of the ground down to the level he. This liner may be of concrete, metal plate, or the like, and is sealed against the rock. EX- terior to the liner there is provided a well 4 which communicates with any cracks in the rock in its vicinity and collects water therefrom so as to provide a free subsoil water surface having the This subsoil water level may be raised at will by lling the well with water so that, in effect, the subsoil water forms a cone of elevation rather than depression around the container. This subsoil water level affects pressures about the lower portion of the cavity and, hence, serves to control pressure and leakage conditions thereat. Desirably, the wall liner 3 is constructed when the blasting of the cavity has proceeded to a level slightly lower than that indicated at hs. The

subsoil water surface will then set itself n'balance in approximate correspondence with the future level during operation. As the blasting or excavation is continued, all the water-bearing cracks and their mouths in the cavity may be 'detected and may be successively sealed or partially filled with cement so that the ultimate inward leakage of water is restricted, if required, to an acceptable value. When the excavation of the cavity has been completed and the cracks have been sealed to the extent desired, the container is lled rst with water and then with oil, the latter taking place during withdrawal' of approximately the same quantity of water. The position of the subsoil water surface may be then observed as well as 'the leakage, if any, as a function of the thickness of the oil layer. In this way there may be determined the operation characteristic of the cavity which will serve for determination of the control of operation in the future use of the container. Control of the leakage of the cavity is valuable in avoiding the necessity for excessive pumping of water flowing thereinto. Lining the cavity at the top has the advantage in that leakage of water into the oil is eliminated at the upper portion of the cavity which is generally that at which most Water inux would occur.

At the left of Figure 1B there is a diagram similar to that shown at the left of Figure 1A but indicative of conditions which may exist for satisfactory storage using the cavity or conof which, is at hoz. The level, at Figure 1B. is

shown.v atvthe extreme upper endof theliner 3v.L

Assuming the subsoil water level hkestablished by the level of Water in thewell-t-to be-thesame 'as inthe case of Figure 1 A, it Willbenotedthat the, curve g; intersects the cur-ve c2c at the level ha which is intermediate the. upper and lowery endsV of the; liner 3l above they level he, Thel oil` pressure exceedsthe subsoil water pressure; and, if,itwere not for the lpresence of the-impervious liner, the oil would now outwardly and so be lost or would contaminatevthe subsoil Water. Below they llevel hr at which subsoil water pressure exceedsvthe oil pressure and, consequently-where thecontainer is4 porous, i. e. belovv'the leveliheA inow of Water will. takeplaoe. described connectionwith Figure lA. At the level ha` for" example, the excess Water pressureover. oilpresf.

sureis indicatedat AF2. As alreadypointed out,

thevamount of this inux mayV be controlled to some extent by. thesealing off of large-ssures-orcracks in the container Wall; however.; somevvilly remain unsealed` andwaterwill accordingly flowinwardly, accumulating; in the pool of; Water below the interface 8.

What hasv just been described indicates the function, of the impervious liner 3 in takingcare of, variations in the subsoil water level andi in permitting a rise in the` level of' the surface of' theoil. So long as the level; of the intersection ofthe curves o2 and gy isy between, thelevel of the upper and lower ends of the impervious liner- 3 the container will function properlywithout-loss Accordinglyi. variations oflevel hgv'withinthe reasonable lime:

ofv oil and withv inux ofwater.

its.. determined byl the impervious linerf will 'be acceptable and, at the same timeit tvvilligeneral-4 1v bepossible to maintain the level of the surf faceof the oil higher with-respect. to.; the; subsoilIv water surface level than in. the case of.I the con.- tainer of Figure 1A.

Referring to Figure 5,7there is-,indicated there inthe minimum desirable verticallyy ex-temiingv impervious vvallt consistent Withcomplete utili,.

zationz of the advantages cf; the inventionf under different conditions of operation. Assumngthat',

the level of the subsoilwater may varybetvveen the limits hgl and hgz, the imperviousglinenshouldl extend-bevondthese levels. The impervious liner should, in anyvcase, include the highest occurring cilx level at thewalls of the container` to prevent the oil from flowing out into thearockiabolvelthef.

upper llmitvof the impervious layer. Itis. furtherA preferable, particularly in storing viscicl ,oi 1,. tohave the impervious Wall include also; thelow-1 est occurring oil levelto prevent drippingofwa.-

ter down into the oil. surfacewith:p0ssib1eatf tendant emulsification. l

Referring again tc Figure 1B,`Wh,e.n oil is; re Y moved through they pipe l0- and replacing. water is-introducedA through pipe 9, theinterfacef. Wlll be. raised. If the water level imv is maintained5 constant or approximately so, the oil.- pressure curve 021 in the diagram wi11,in effectcmovetoward the left because it must stillintersect; the stationary line v2 for the water pressureat the, level of the interface 8 which is nowhigher. The. excess pressure of the subsoil Water over the,y oil' thus increases and, accordinglyl there also. in.

l water having the levely hy.

drawal of-v the--Water-through pipe spermitting seepage to supply additional Water, the pressure differential may be kept at a suitable constant value to maintain approximately constant the rate ofinflux of Water.

The advantages of a cavity having an impervious liner` at the upperv portion thereof will,4v now. bewclear. Not only canA the oil level be higher, giving the advantage of larger storage volume while still preventing loss of oil eventhough in the uppermost portions of the conrainerA theoil pressure may exceed the subsoil. Water. pressure, but variations in level of the subsoil water will nct, within the limitations for which4 thedesign is made, result in the existence of conditionsinconsistent With` proper` storage, i.-e. excess of oil pressure at any levelcover the; subsoilA Water pressure Where the walls'- arezpervir 0115'.

has-thedrawback that the impervious Wall in the upper portion of the cavity has the same large` circumference as the` container itself. Considerable improvement is; obtained by making the up-r cer imperviousportion of the; cavity in the form of a verticall or other upright shaft having a comparatively small circumference and, consesilently,V comparatively. low construction cost. Due to-thefact that the shaft may be restricted in circumference itmaysometimesbe made imperviousfto both oil and Waterisimplyby selecting the location of the shaft so, that` the rock ai lake,r a. river or a pond or some otherv body ofv Water of: substantial volume. The subsoil water is` around the entire container and is artificially raised to; and` maintained at, thel level hg at theglourld: Surface` through; an additional supply of l Water` through the cracks and their mouths in the ground surface and; in the interspaceA or- Well 4. The lower portion, of the cavity may, if de sired,l communicate through a horizontal tunnel 24jand a. vertical bore 25 with the supply,- of; The pressure liner g for the, subsoilwater around thecontainer starts at theflevelhg, of: the ground, surface. The pressure line 1; for the water in the supply pipe 9V star-ts fromv the surface hy because the water in f, thecontainer communicates. with the water ac.

cumulationv through the tunnel 24' and the bore 25. The pressure line o for oil, the inclination of whichy is determined by the specic gravity of` the cil, extends fromvtheintersection ofA the; pressure line v with the level of the interfacesbecause the pressures of the water and of the oil:

' laver. The topvlayer of theoil in the case illustrated is levell with the subsoil water surface and creases the leakage of, Waterbelow the lgojtorrlV of: S indicated at he. Thepointsof intersectionbeg,

kThe actual container b shown in Figure l-IBV;l

7. tween the horizontal line ha from the lower limit (il of the impervious liner 3 with the pressure lines g and o indicate that at the lower portion of the liner the subsoil water pressure is the quant-ity Ap higher than the oil pressure at the same level so that oil cannot flow out of the container. If the surface of the water accumulation having the level hv rises, or if the oil has a lower specific gravity, the oil level will rise and the quantity Ap will be reduced. This is permissible so long as the quantity Ap is positive. If the water level Ihv is reduced or the oil is heavier, the oil surface will fall below the subsoil water surface hg. Then the quantity Ap rises and the leakage of Water into the container will increase. If there is a leak in the cavity wall at a point such as II which communicates with the water accumu lation at the level hv but not, or at least not to the same degree, with the surrounding subsoil water, oil would ow out into the rock under the pressure Apl. In the diagram the line for the subsoil water pressure may then appear asindicated by the dashed line g1. The fundamental condition for the provision of raised subsoil water around the upper portion of the cavity in Figure 2 is either that the natural subsoil water pressure is suiiiciently high around the lower portion of the container and higher than the pressure p or that the water pressure there is raised through one or more bores 23 acting as shielding holes, which bores are supplied with water and cross the cracks, if any, in the formation so that the subsoil water pressure is sufficiently raised around the lower portion of the container, for example, according to the curve g2.

Full guarantee against oil leakage from the lower portion of the container is gained, however, if the oil level is lowered to a height corresponding to the lowest subsoil water surface hv.

' In Figure 2 the walls of the shaft are made tight by means of a concrete wall or liner 2 joined rmly with the rock as by casting. Reference may be made to Figure 6 wherein there is additoinally a horizontal tight roofing surface I2 through which the necessary pipe lines extend in tightly fitting relationship to prevent gases from forcing their way out.

In storing viscid oils it is often necessary to heat the oil before it can be transported through pipe lines. The heating can be performed so that the oil when being withdrawn from the container will have to pass a space provided with a heating coil. According to the present invention, the space I3 in Figure '7 may be used for this purpose. The heating coil 20 is lowered into the space I3 and may be raised up for supervision of its operation. This space is covered by lid 2l. The heated oil is Withdrawn from the upper portion of the container through the oil line Iii. The water line 9 is heat insulated. Through this arrangement a considerable portion of the plant cost for an additional heating chamber is saved.

Figure 3 shows a container b such as might be used for the storage of combustible oil for engines. The wall-s of the shaft at the upper portion of the container are tight as in Figure 2. Further, there is in the lower portion of the shaft a tight cover I 2 constituting part of the wall of the oil space which is tightly joined to the walls of the liner and through which the water line 9 and the oil line II! extend with tight fit to prevent leakage thereabout. The interspace or well A and the ground surface around this are filled with water up to the level hg either artificially or by means 'of subsoil water from a higher level. It may be assumed that this container is adjacent tothe sea indicated at 21. Toward the sea side the subsoil water surface will then slope downwardly toward the level hg1. In the upper portion of the container b the subsoil water pressure depends on the subsoil water level hg in accordance with the line 9 in the diagram and the oil may be stored with a safety margin of pressure Ap as indicated by reference to the oil pressure line o. From this the pressure line o is obtained for the corresponding water pressure in the pipe line 9 having an upper water surface at the level hv. In pumping oil into and out of the container through the pipe line I, the supply and Withdrawal of the water must be controlled in such a manner that the water pressure in the pipe line 9 does not rise so high that oil is forced out into the rock. This is rather difficult to accomplish if the lines 9 and It continue out of the container with directly connected lines, as indicated by the pipe 9c drawn in dashed lines and the pipes 9a and I0, respectively, in full lines. It is preferable to have the line 9 open into a buffer space I3, i. e. a reservoir having a considerably larger cross sectional area than the pipe line and to control the pumping into and out of said reservoir. In the lower portion of the space I3 the pipe 9 has an open end whereas junction pipe 9b opens at its lower end into the space I3 and is connected at its upper end to the pipe 9a.

According to the principles recited above in connection with the pressure diagram, the water in the space I3 reaches the level hv. The external water line 9a has a pair of pumps I5 and I1 which may be operated automatically, if desired, for the removal and introduction of water to hold the water level at hv or lower. If the rock around the container b in Figure 3 communicates with the water accumulation having the level hgi and it is desired to store the oil under such conditions, the oil and water levels in the container may be regulated to hor and hvi, respectively, in which case the excess pressure Api of the water in relation to the oil at the level he will be as indicated by the dashed lines of the diagram. However, the oil and water levels in the container may be controlled at lower levels hoz and hvz in which case the excess pressure of the subsoil water over the oil pressure at the level he becomes considerably higher, i. e. Apz and Apc in relation, respectively, to the lowest and highest subsoil Water levels. From this it will be seen that it is possible according to the present invention to regulate the pressure conditions within a very wide limitation while maintaining good safety margin with respect to oil leakage.

Figure 4 shows a storage container particularly for gasoline. The tight zone of the container includes both the shaft and a portion of the cover of theA container b at 22. The subsoil water has been raised to the level hgi and the shielding hole 23 communicates with the subsoil water at its elevated surface. The aqueous communication with the bottom of the container extends through `available on a-tank boat inthe wateraccumulation 21 supplying'the gasoline. The'gasolineis Withdrawn'by thepump'l'. The 'gasolineline lo opens :slight-ly 'below the 'tight 'cover lsurface' |72 :so that there 'is formed an air cushion between 'the Astored gasoline surface andtheulocderside `of .the cover 'r2 to Yprotect thisiuter alla', against the chemical action of the gasoline. Provided .thatfor safetys sakeand in accordanceA with the pressure line -g the subsoil waterreierring-to the Water surface?! has the lexcess*pressure Ap in rlation'to the voil pressure' at the `lowernic'lst por tion'29` Aof-the tight 'Zone in theeontainenthere .is 'obtained pressureline `o 'for the gasoline, and, from this, pressureline '1i vfor the water inthe container having vits-'free surface yat the level hv the ,reservoir ,26. The highest level ofthe Y'gasoline should he athe, i. e. higher thanv thepipe line 4I o'. Through a valve' 23' thegasoline ls,how ever, prevented from flowing out of the container. VBy displacement Yof the pressure line o to the left the safety margin p may lo'e'ir'lcreased. `In practice, thisV condition is realizedb'y lowering the water level in the reservoir '2e and thus' lalso the ga-solinelevel he. Because under all conditions thewater level in the container 2t in this case will loe lower thanthe subsoil water surfaces tgi and'hg, Ait may he preferable to Vpr' 'iv'iole va shielding hole between the reservoir'Z and the container b. y

'In Figures 6 and 8 to 12 there are shown some furtherjarrangements of the tight upper portion of the cavity and its surrounding subsoil. water. In Figure 6 in'which the oil Vis considerably lower than ,the surroundingV subsoil water the Walls 2 need not, according to the .present invention, ,be completely impervious because,v in any case, the oil" is prevented from flowing out through .the walls due to the overpressureexerted by the leaking-in subsoil water. It is, however, advantageous tomake them impervious to water to prevent `the dripping of waterinto the con-.

tainer adjacent to the withdrawal pipe I for the oil.

Figure 8v shows the shaft shut off at its lower end hya tightA cover' l2 which formsvpartof the wall of the oilspaceand, together with the wall Il, a cup whichis maintained filled with Water up to Athe subsoilwater level hg with the result that it communicates with the subsoil water both adjacent to the ground surface and through the cracks in the wall Il. The water layer at the ground surface is covered by a loose stonevlling 30 and above this. there .is a concreteiloorrl.. Water "is supplied at 3l through this floor `and any excess thereof runsol at overnow drain-5'.

AFigure 9 shows asimilar arrangement butthe cover orwall I 2 isY Yhere adapted Vto be slightly permeable Yto water drops to protect the surface ofthe cover against damage by the oil.VV The water level in theshaft is in this case .slightly hgherthan'theatural levelhg. l r 'Figure 1'0 shows an arrangement rather similartothat of Figure 9`but showing the walls entirelytight. Articial -supply of water is arranged'both tothe cup-r I3V and to the well 4 out#- ei-de-she wenz. A l

Figure 151 showsr a shaft having tight Walls'l andi'atight cover |2 with vpipe* lines li!" and I0 for` 'water'andoiL respectively, projecting' through the Water is lled into the'spaces 4 and 35 between.

the rock and the impervious -wal1'2 and concrete floor 32, respectively. Thisfvfloo-r is-tig'ritegelnst therocl: at l33 'andfis secured to the rock with bolts 34. The shielding holes 23 communicate with the water in theinterspaces 35. JThis disposition lof-sulosoil water 'elevated 'above the licor is'preferred particularly if the naturalsubsoil Water level o-f the rockfs to belnaihtainedinelevated position. Y l Y Figure 12 Yshows an arrangement rathe'sinlilar' tofthose shown Figures 6,19and 10 brita/pplied to a 'cavityin the' rock'having an irregular fr 'ild With th-'natural SubSolI limiterV lV'lS and ha reisen to he and ha. The 'rightliand sdeof lFigure 12=shows inthe upper part of the container wall a section which isv devoid of sealing ineens' extending frombelow the oil surface he and `the cover Or-upper ypartV of the wall l2. Due tot-he' high subsoil water levels he and hei. respectively, the'wall is, according to the present invention, tight against o-il tending to forc its Way'ouf'thrugh'th'WlL 'While not ShW in Figure 12, it `Will be understood that the Oil floats one body of water as in Figure 4 and as in this Same'Fgule 4 the Water ln the bttOin 0f the e tainer communicates with a reservoir corresponding to 26 in Figure 4. Y

'Ihe drawingsdo not show' any cover manholes, but these should be provided wherever required. The cavities'may'lleY` shaped in different fashions. Itis, however, preferable to make the ycrmtainer adjacent to the shaft sharply vaulted to obtain sullicient strength and ability to divert leakage. The shaft may, of course'be placed in any desirable position and even laterallyof the main cavity. The Walls of the container may consist-of rock, concrete and/)or other materials, whereit is of importance to prevent the escape of oil lor other fluid.

Of the various embodiments of the invention shown by way of example, t-ho'se illustrated Lin Figures 3, 4, 6, 8, 9,'1'0', 11 and l2 are Vgas-tight which is of importance when volatile oils arebe ing stored. r l e The introcuctionof oil into the container will generally beperforrned utilizing the'pumps'ofa ship, Whereas the 'withdrawal ofthe` oil' may be' accomplishes with pumps suon as heretofore in'-l dioeted at ls in Figure zloeeted attire ground surface-or further down in Va shaft'or in a vpipe line1 projecting downwards. WhenrequiredVV the water'may be' supplied andwithdrawnby a pair of lpurllp's one at'e'ach end ofithewaterline and arranged in such a manner that, as in the case ofthe oil Ipumps,the suction lift will not bie too great". A Vsingle 'pipe line is Vpreferably Vused 'for transporting reach A'liquid in looth .directions 'in which'4 case the idle pump' may be shunted in knowrrnranneras 4is indicated in Figure 2 with respectitojthe pump A|16 in the oil'line' IU.

The 'water pump' |25Y for outgoing waterfis rpreferably provided with automatic starting and stoppingl -devioe's Ycoirnn'lien by the.' water or oil level or yby the pressure so'tha'tvleakage Water may be pumped out whenever requiredv before .the water' level risesabove an' allowablemaximum height'. As' 'ab'ove stated, it 'is tobe preferred-.if the removal, of'water may bei accomplishedfrom areservoirhaving ararg'erree Ywatersurface asfat |3in-Figure 3 or26 Figure 4; y

The water p'ul'rlpsv may be dispensed with if, as' in' li'figulerglthe lva'ter line is made to establish communication between' the bottom of the oon'-y t'azlneit -17 and' the vwater accumulation 21 orif a epeal Connection-JS. arranged ,throne-n tunnel 11 24 and bore or shaft 25. In the iirst instance, the water line 9a must be provided with an evacuation pump I9, Figure 2, which removes air from the uppermost portion of the line. In both arrangements the transporting of water into and out of the container takes place automatically so that the oil level may be held at a suitable nearly stationary position.

I claim:

1. An underground container for storing waterimmiscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, and means for maintaining the pressure exerted by the stored fluid at any point on the pervious Wall on the container at a pressure less than that exerted by the su'bsoil water at the same point.

2. An underground container for storing waterimmiscible iluids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water column substantially isolated from `the stored fluid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary for said cavity in the upper portion of said cavityJ and means for maintaining the pressure exerted by the stored fluid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point, said lastnamed means including a bore hole adjacent to said cavity and communicating with a source of water.

3. An underground container for storing waterimmiscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious Walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water r column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary for said cavity in the upper portion of said cavity, said substantially impervious means forming the bottom of a Well for the reception of water, and means for maintaining the pressure exerted by the stored fluid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

4. An underground container for storing waterimmiscible fluids having specific gravities less than thatof water comprising a cavity in the earth having pervious walls exposed to external lsubsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water column substantially isolated from the stored uid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary for said cavity at the upper portion of said cavity, and means for maintaining the pressure exerted by the stored l2 fluid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

5. An underground container for storing waterimmiscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary for said cavity in the upper portion of said cavity, said substantially impervious means having an annular well about a portion of the exterior thereof for the reception of Water, and means for` maintaining the pressure exerted by the stored fluid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil Water at the same point.

6. An underground container for storing waterimmscible uids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a water column substantially isolated from the stored liuid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary for said cavity in the upper portion of said cavity, means for withdrawing the stored fluid at a point near the top of said cavity, and means for maintaining the pressure exerted by the stored fluid at any point on the pervious wall of said container below Said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

7. An underground container for storing waterimmiscible iiuids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the' level of said water layer, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, a substantially impervious liner in the upper portion of said cavity, said liner having a substantially fluid-impervious bottom therein and pipe means extending through said bottom, and means for maintaining the pressure exerted by the stored uid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

8. An underground container for storing waterimmscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the -level of said water layer, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary in the upper portion of said cavity, said impervious means hav.- ing a substantially impervious top thereon, and

means for maintaining the pressure exerted by the stored fluid at any point on the pervious Wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

9. An underground container for storing waterimmiscible fluids having speciic gravities less than that of water comprising a cavity in the `earth having pervious walls exposed to external subsoil water and having a Water layer in the bottom thereof, means for varying the level of said water layers, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored fluid, substantially impervious means providing a boundary in the upper portion of said cavity, said impervious means having a top thereon and an annular well around a portion of the exterior of sid impervious means for the reception of subsoil Water, and means for maintaining the pressure exerted by the stored uid at any point on the pervious Wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

10. An underground container for storing Water-immiscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a Water column substantially isolated from the stored iiuid and in communication With said Water layerV beneath the stored fluid, substantially impervious means providing a boundary in the upper portion of said cavity, a heating coil positioned `adjacent to said substantially impervious means to lower the viscosity of the stored fluid, and means for maintaining the pressure by the stored fluid at any point on the pervious wall of said container below said substantially impervious means at a pressure less than that exerted by the subsoil water at the same point.

1l. An underground container for storing water-immiscible fluids having specific gravities less than that of water comprising a cavity in the earth having pervious Walls exposed to external subsoil water and having a Water layer in the bottom thereof, means for Varying the level of said water layer, said means providing la Water column substantially isolated from the stored `fluid and in communication with said water layer beneath the stored fluid, and means for maintaining the pressure exerted by the stored fluid at any point on the pervious wall of the container at a pressure less than that exerted by the subsoil water at the same point, said last named means including a bore hole adjacent to said cavity and communicating with a source of water..

12. An underground container for storing Water-immiscible fluids having specific gravities less than that of Water comprising a cavity in the earth having pervious walls exposed to external subsoil Water and having a water layer in the bottom thereof, means for varying the level of said water layer, said means providing a Water column substantially isolated from the stored fluid and in communication with said water layer beneath the lstored fluid, means for maintaining the pressure exerted by the stored uid at any point on the pervious wall of the container at a pressure less than that exerted by the subsoil water at the same point, said last named means including a bore hole adjacent to said cavity and communicating with a source of Water, and means for withdrawing the stored fluid at a point near the top of said cavity.

13. An underground container for storing water-immiscible fluids having specic gravities less than that of water comprising a cavity in the earth having pervious walls exposed to external subsoil water and having a water layer in the bottom thereof, means for varying the level of said Water layer, said means providing a water column substantially isolated from the stored fluid and in communication with said water layer beneath the stored uid, a shaft connecting said cavity With the atmosphere, a fluid impervious liner 4closing said shaft, pipe means extending through said liner, and means for maintaining the pressure exerted by the stored fluid at any point on the pervious Wall of said container at a pressure less than that exerted by the subsoil water at the same point.

14. An underground container for storing water-immiscible fluids having specic gravities less than that of Water comprising ya cavity in the earth having pervious walls exposed to external subsoil water and having a Water layer in the bottom thereof, means for varying the level of said water layer, said means providing Ia water column substantially isolated from the stored fluid land in communication with said water layer beneath the stored fluid, means for maintaining the pressure exerted by the stored fluid at any point on the pervious wall of the container at a pressure less than that exerted by the subsoil Water at the same point, and heating means for lowering the viscosity of the stored fluid.

HARALD EDHOLM.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 303,506 Goodridge Aug. 12, 1884 744,694 Sewall Nov. 17, 1903 1,921,358 Hill et al Aug. 8, 1933 2,333,315 Klingberg Nov. 2, 1943 21,459,227 Kerr Jan. 18, 1949 

